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R Southgate

Publications and source records attributed to R Southgate.

31 records · Page 2Linked to original sources
PubMed1982

Regulation of heat-shock genes: a DNA sequence upstream of Drosophila hsp70 genes is essential for their induction in monkey cells.

Heat-shock genes coding for heat-shock protein 70 (HSP70) in Drosophila melanogaster were subcloned into an SV40/plasmid recombinant capable of replication in permissive monkey COS cells. Following transfection of COS cells, no significant amount of Drosophila hsp70 RNA was detected at 37 degrees C. In contrast, a heat-shock at 43 degrees C or arsenite poisoning at 37 degrees C induced the massive production of Drosophila hsp70 RNA of correct size and faithful 5' ends. After heat-shock, the efficiency of hsp70 transcription in COS cells containing 2-4 X 10(4) gene copies was found to be 15-30% of that measured in Drosophila, on a per gene basis. By testing a series of 5' deletion mutants in this inducible transcription assay it was found that a sequence less than 70 bp long, directly upstream of the hsp70 gene, was essential for the heat or arsenite induction of transcription.

Animals↗
PubMed1981

A DNA segment isolated from chromosomal site 67B in D. melanogaster contains four closely linked heat-shock genes.

cDNA clones coding for two different small heat-shock polypeptides were isolated. Both clones hybridize exclusively to the heat-shock puff site 67B, and restriction mapping of embryonic Drosophila melanogaster DNA showed that the two genes probably occur as single copies and are closely linked. The analysis was extended by isolating genomic clones, which contain these genes and two additional ones. The four different genes code for heat-induced poly(A)+ RNAs. These genes are clustered within an 11 kb segment and are separated by spacers of 1.0-4.7 kb. Three of the genes were found to exhibit alternating polarities. Thus in spite of their close linkage, the four heat-induced genes are most likely organized in individual transcription units.

Chromosomes↗
PubMed1977

Structure--activity relationships in cephalosporins prepared from penicillins. 1. 7beta-Acylamino derivatives of 3-benzyl- and 3-(3-pyridylmethyl)ceph-3-em-4-carboxylic acids.

tert-Butyl 7beta-aminoceph-3-em-4-carboxylates carrying either benzyl or 3-pyridylmethyl substituents at position 3 have been prepared by a multistep modification of the penicillin nucleus. Acylation of either amine, followed by deprotection, gave a range of new cephalosporins. The relationship between structure and antibacterial activity is discussed. D-Phenylglycine proved to be a preferred side chain in both series.

Benzyl Compounds↗
PubMed1977

Structure--activity relationships in cephalosporins prepared from penicillins. 2. Analogues of cephalexin substituted in the 3-methyl group.

A previously outlined general procedure for preparing various 3-substituted cephalosporins from the penicillin nucleus has been used, with modifications where required, to prepare a series of analogues of cephalexin with various substituents in the 3-methyl group. The 3-substituents most conducive to broad-spectrum antibacterial activity were 3-pyridylmethyl and m- or p-carboxybenzyl. The compounds were only poorly absorbed by the oral route in mice, but the 3-(carboxybenzyl) compounds gave more prolonged useful serum levels than the usual cephalosporins.

Animals↗